Unveiling significant changes in optical, magnetic, and visible-light photocatalytic performance of CuFe₂O₄ nanocompositions through chelating agent modulation

This study presents a comprehensive investigation of copper ferrite (CuFe₂O₄) nanoparticles synthesized using the sol-gel auto-combustion method with three distinct chelating/combustion agents: glycine (GCF), succinic acid (SCF), and tartaric acid (TCF). The choice of chelating agent significantly influenced the structural, morphological, magnetic, and photocatalytic properties of the CuFe₂O₄ nanoparticles. The synthesis of high-crystallinity CuFe₂O₄ was achieved using glycine and succinic acid, resulting in certain impurities, namely Fe₂O₃ and CuO. In contrast, the tartaric acid yielded the purest form of CuFe₂O₄, containing only trace amounts of Fe₂O₃ while exhibiting lower crystallinity. Importantly, both tartaric acid and succinic acid significantly reduced particle size and surface roughness. Variations in the position of IR bands indicated changes in cation distribution within the Oh sites influenced by chelating agents variation. Optically, a significant red shift in the absorption edge was observed with an extended absorption tail into higher wavelengths, likely attributed to morphological variations in the nanocrystals. The GCF sample exhibited a band gap (BG) value of 1.56 eV, while the SCF and TCF samples displayed BG values of 1.64 eV and 1.60 eV, respectively suggesting the suitability of these ferrite powders for solar energy photocatalysis applications. The refractive index (n) values for the GCF, SCF, and TCF samples were recorded to be above 2.5, indicating their high refractive indices. Among the samples, GCF exhibited the highest refractive index value. A significant increase in coercivity was observed when transitioning from tartaric acid (530 Oe) to glycine (931 Oe), while an even more dramatic increase was recorded for the SCF sample, synthesized with succinic acid (1275 Oe). This demonstrates the substantial impact of the chelating agent on the magnetic coercivity of the CuFe₂O4 nanoparticles. The photocatalytic activity of CuFe₂O₄ nanoparticles was preliminary evaluated using the degradation of congo red dye under solar irradiation. GCF exhibited the highest photocatalytic performance (96 %), followed by SCF (92 %) and TCF (39 %). This superior performance can be attributed to the higher crystallinity and presence of free CuO and Fe₂O₃ phases in GCF and SCF, which likely facilitated charge carrier separation and transfer. The degradation process followed a pseudo-first-order reaction, as evidenced by the linear relationship between ln(C_t/C₀) and time.